Highly filled polymer systems are used extensively in commercial applications, such as flame retardant (FR) and halogen-free flame retardant (HFFR) applications, sound management such as sound deadening applications, flooring applications, wire and cable applications, polymer master batches, roofing membranes, wall coverings, and automotive applications. Likewise, such highly filled polymer compositions can be used as highly filler loaded master batch.
High to very high melt flow rate polyolefins such as polypropylene and polyethylene homo- and copolymers are used in this field with the limitation to accept high levels of filler and with poor processability and mechanical properties. This does significantly limit their use in the fabrication of finished articles and as a pigment/filler master-batch. At high filler loading the homogeneity is generally low.
It would be desirable to utilize very high levels of filler for these applications, typically at least 15% by weight, preferably at least 30% by weight, further more preferably at least 35% by weight, even more preferably at least 40% by weight, and if achievable, at least 55% by weight and up to 85% by weight filler. However, few polymer compositions are able to incorporate these levels of filler, while still maintaining the performance properties necessary to effectively fabricate the filled polymer compositions into fabricated articles. In particular, propylene-based polymer compositions have not been available that can incorporate the required level of fillers while still maintaining the desired physical properties, such as flexibility, tensile strength, extensibility, elongation, heat resistance, low temperature flexibility, and thermoformability and thermostability during processing.
What is desired is a propylene-based polymer composition that is capable of incorporating large quantities of inorganic and/or organic filler, while simultaneously exhibiting an enhanced balance of physical and mechanical properties as well as good processability for the applications of interest.